Well said NRBQLou: I think some of us AV enthusiasts fall for the trap of purchasing new electronics to get the latest features without considering the efficacy of said features. Audio DSP soundfields are a a good example of this. They sound great on paper but poor in practice. Ironically, one of the best audio surround processing modes I've used is also one of the oldest and easiest to implement: Ambiance extraction via Hafler's L-R, R-L surround system. I used this system with Theta's Casablanca prepro and it's a feature I wouldn't want to live without it now. If memory serves, Dolby ProLogic II works on the same principle but I haven't gotten around to trying it out yet.

I owned the 990 a while back and really enjoyed it. In terms of bang for the buck, I've never owned a better prepro, and it's why I'm holding out for the 978 now. Ironically, a single feature swayed me to the 978 versus the Marantz AV7005 which does most of what I need: Audyssey XT32. I have dual subs and will be building speakers in the near term that will benefit from the higher resolution XT32 offers versus XT.

Having said all this, if the 990 works for its owners today I don't think they should rush out to replace it until the 978 becomes available. Despite its age the 990 holds up very well in terms of build, reliability, and sonics relative to anything near its original SRP.